The P183 shipped with two 120mm Antec TriCool fans installed in the rear and
top placements with manual 3-speed switches attached to the back of the case.
When we turned them on we noticed immediately how much louder the top fan was.
The top-mounted fan measured 5 dB higher when set to low and medium speed, and
7 dB higher at high speed  the rear fan was completely drowned out. When
the two fans were removed and allowed to spin in free air, they sounded identical,
so it was clear the problem lay in the fan mount.

Top fan placement from the inside.

At the top of the case, cutouts in the metal allow air to pass through. We believe the remaining metal outline of
the fan hub and struts is the reason the top fan sounds so much worse when mounted
compared to the rear fan. As a result, the top of the case vibrates heavily
when a fan is mounted in this position. Why a complete
circle wasn't cut instead is a mystery  there is absolutely no reason to leave a metal
tracing of the fan structure. In addition, as the top panel of the case cannot
be removed, and there is little clearance between the metal and the plastic
grill above it, cutting this piece out will prove problematic. Decoupling the
fan would certainly help, but this is also no easy task, as only one side
of the fan is secured with screws. The other side has two metal tabs that keep
the fan flush against the metal surface. This is an odd annoyance in an otherwise well evolved case.

Baseline Noise

Noise measurements were made of the case with the two supplied 120mm fans at standard switch settings and configurations we think most silence-oriented users will try. The air cavity resonances inside a case amplify fan noise, as do any vibrations transferred from the fans into the case, so these measurements can be regarded as the baseline SPL levels for the P183 with the stock fans. Changing the fans is a very simple option, as a huge variety of 120x25mm fans are available in the marketplace; it should be easy to obtain ~2 dBA improvements in any of these configurations with better fans.

Antec P183 Baseline SPLThe back exhaust fan was a constant; the other fan was positioned either on the top panel as an exhaust or at the front as an intake. L=low spedd; M=medium speed. Measuring mic positioned 1m at diagonal angle left/front of case.

back exhaust

top exhaust

front intake

SPL

L

-

-

15 dBA

L

-

L

17 dBA

L

L

-

21 dBA

M

-

-

25 dBA

M

L

28 dBA

The perceived noise is low and smooth with all configurations when both fans are set to Low. Turning any of the fans to Medium pushed the SPL too high for us to consider acceptable in a quiet PC. With both fans set to Low, the quietest configuration was back panel exhaust and front panel intake, which measured 17 dBA, a significant 4 dBA lower than when the front fan was moved to the top. Removing the front fan dropped the SPL by 2 dBA, which was clearly audible in the anechoic from a meter away, but perhaps it would not be as plainly audible in a room with higher ambient noise. Depending on exact case positioning vis-a-vis the user/listener, closing up the top vent could effect a slight reduction in noise, but as that vent actually plays some role in bringing cooler outside air to the CPU area, cooling might be affected. As with the earlier versions of the case, experimentation with fan configuration for your particular setup is worthwhile if you seek the very best results.

Test Results - Configuration #1 (IGP)

Case with test system installed (integrated graphics).

For our IGP test configuration we left only the rear system fan on low speed.

Housing a system with a 125W CPU, quality CPU cooler, and integrated graphics,
the P183 did very well even with a single exhaust fan. Southbridge and hard
drive temperatures were both below 40°C, and barely increased with load.
The CPU fan was run at 70% as doing so increased the noise level slightly. The
CPU temperature increased by 20°C when the system was stressed.

The noise level of the system measured between 19 and 20 dBA, and was very
benign and smooth. The multi-layered panels do a good job of helping to damp and soften the internal component noise. Antec would do well to decrease the speed of their TriCool fans, however, as
their medium and high speed settings are much too loud. The Antec CP-850 power
supply performed well, not adding any perceivable noise to the system.